Integrated circuits are generally produced on a semiconductor wafer, which is generally disc shaped, in regions of the wafer that are separated by slicing lines. After production of the components of the various integrated circuits in the substrate of the wafer, and production of the interconnection parts (commonly referred to as BEOL: Back End Of Line) of the integrated circuits, the wafer is cut into individual chips by slicing it along the slicing lines.
Deposition of the various layers as well as the diverse etching operations are performed on the whole wafer. Among the operations performed include the formation of the electrically conducting contact pads, referred to more simply as contacts. The contacts link tracks of the first metallization level of the interconnection parts of the integrated circuits to electrically active regions of the circuits, for example, source, drain, gate regions, or polysilicon lines forming resistors, for example.
The formation of these contacts comprises etching an electrically insulating layer disposed above the substrate of the integrated circuits so as to form orifices or vias which will thereafter be filled with an electrically conducting material. The electrically conducting material may be metal, for example, such as tungsten.
In certain cases it turns out that integrated circuits, or in the worst case, certain wafers exhibit, especially in their central region, contacts that are not fully etched. This means that the contacts are non-emergent. Therefore, these contacts do not allow for an electrical link to be established between the corresponding metallic track and the underlying active region. These circuits or wafers may then become unusable, which is undesirable, especially in terms of production costs.